The story behind these numbers is interesting, and important. To begin with, it would be easy to look at the report’s chart on deaths from cancer and heart disease and conclude cancer deaths are climbing at a rapid pace. In fact, cancer death rates continue to drop at about 1% to 2% per year. The number of deaths is increasing, but that’s only because we have a growing, aging population.

As for the closing gap between cancer and heart disease: while cancer death rates have been dropping since 1990, rates of heart disease deaths were dropping even faster and for a longer time: by more than 2% a year, and at times as fast as 4%, from at least 1969 to 2010.

The American Cancer Society was among those who had estimated that cancer would overtake heart disease as the leading cause of death overall in the United States during the current decade. But, as so frequently happens, reality stepped in: the death rate from heart disease has begun to flatten, possibly due to rising rates of obesity, or perhaps because we are reaching a limit on our ability prevent deaths from heart disease. Meanwhile cancer death rates continue their steady descent. That change in heart disease deaths slowed the closing gap.

Another interesting aspect of this: those states where cancer has overtaken heart disease are actually doing better overall, with generally lower death rates for both heart disease and cancer. It’s because heart disease deaths are so low in those states that cancer is the top cause of death.

Finally, there’s the age factor. We frequently say cancer is a disease of aging. That goes double for heart disease. Cancer is also the leading cause of death in the U.S. in people ages 40-79 years because heart disease tends to occur at even older ages than cancer. In fact, the reason cancer is the leading cause of death in Hispanics and Asian/Pacific Islander populations is because these are younger populations, not because they have more cancer. Indeed, heart disease is the leading cause of death in these populations in the older age groups (80+).